Client cpp with all features

[jonyMarino]

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Fixes: #13

About

Add Project AirSim C++ client, packaging, docs, tests, and CI

Description

This PR adds the new native C++ client for Project AirSim and modernizes its build/distribution flow.

What Changed

• Added the CMake-based C++ client build under client/cpp.
• Replaced legacy Visual Studio project-based client builds with CMake/Ninja targets.
• Added ProjectAirsimClientLib and ProjectAirSimMessageLib as CMake-built libraries.
• Added a final merged static library package target:
  • Windows: ProjectAirSimCppClient.lib
  • Linux: libProjectAirSimCppClient.a
• Added install/package support through CPack, including:
  • versioned client archives
  • public headers
  • examples
  • scripts
  • CMake package config files
  • package README
• Added C++ client examples and scenario runners for drones, rovers, sensors, lidar, radar, static sensors, and environment actors.
• Added C++ client unit/integration test scaffolding with fake NNGI support.
• Added documentation for the C++ client and linked it from the docs index.
• Updated build scripts to support:
  • cpp_client_debug
  • cpp_client_release
  • package_cpp_client
• Improved build.cmd Visual Studio/MSVC detection:
  • supports standalone builds without UE_ROOT
  • uses the latest installed MSVC toolset when Unreal-specific pinning is not required
  • handles Program Files (x86) paths safely
• Added GitHub Actions CI for the C++ client on:
  • Windows 2022
  • Ubuntu 22.04
  • Ubuntu 24.04
• Added CI smoke tests that build a consumer project using find_package(ProjectAirSimCppClient) and ProjectAirSim::Client.

Notes

The package exposes a single final static library for consumers instead of requiring users to link multiple internal libraries directly.

How Has This Been Tested?

• Built and packaged the C++ client locally on Windows and Linux.
• Verified the generated package can be consumed by an external CMake project.
• Ran actionlint against the new GitHub Actions workflow.
• Ran git diff --check.

Screenshots and videos (if appropriate):